Sacramento Region Transportation Adaptation Plan and Regional Transportation Plan
The Sacramento Area Council of Governments (SACOG) developed a high-level vulnerability assessment and adaptation plan (“Adaptation Plan”) for the region’s transportation infrastructure, and is using the plan as a framework to guide future adaptation work and inform planning for transportation investments. The initial findings from the Adaptation Plan are being incorporated into the region’s 2016 long-range transportation plan update. The Adaptation Plan looks at risks to transportation from four primary climate-related threats to the region: extreme temperature; wildfire; precipitation, runoff, and flooding; and landslides.
To assess the Sacramento region’s climate threats, SACOG used information from Cal-Adapt, an online tool produced by the California Energy Commission. Cal-Adapt provides access to existing climate research relevant to California and allows users to visualize this information through interactive tools. SACOG used Cal-Adapt to assess Global Circulation Models and emissions scenarios to project trends for the region for maximum temperature, precipitation, runoff, and fire. Based upon this analysis, SACOG projects the following effects from climate change including:
- Under the higher emissions scenario, increases in average summer temperature to 95-degrees region-wide, and to as high as 105 degrees in some parts of the region by 2099;
- A “worst-case” scenario for the critical month of January of 28 percent increase in precipitation by the period 2041-2070, causing runoff to increase by as much as 117 percent (compared to the 1980-2010 baseline average);
- In some forested parts of the SACOG region, an increase in wildfire risk by a factor of three to four by 2085 under the higher of the two emissions scenarios; and
- Though more difficult to project, an increase in the frequency and magnitude of landslides due to projected increases in rapid snowmelt and high intensity storms in the future.
The Adaptation Plan discusses the consequences of each of these four key climate threats for different transportation asset types and transportation operations, and in separate appendices identifies best practices for planning, design, and operations and maintenance to mitigate the risk from these threats.
- Extreme heat and fluctuations in temperature can cause pavement deterioration, expansion of bridge joints, heat kinks and buckling of railways, expansion of overhead lines that supply electrical power to trains. It can also cause operational strain by affecting electrical equipment and power distribution systems, and can increase likelihood of vehicle breakdowns. The Adaptation Plan identifies actions that can be taken to mitigate these risks including adjusting temperature thresholds for design standards, using heat-resistant materials, and modifying train load size and speed restrictions to reduce track stress.
- Precipitation, runoff, and flooding can cause road deterioration in a variety of ways, including by allowing water infiltration between pavement layers, separation of pavement materials from binders, and corrosion of reinforcing steel, which can cause concrete to crack. It can also increase risk of bridge scour, erosion of railway substructures, clogging of drainage structures, and power outages. The Adaptation Plan recommends identifying route alternatives in planning processes, restricting development in floodplains, using “living levees,” increasing culvert capacity, using permeable pavement materials, increasing pump capacity, and ensuring drainage systems are clear during heavy precipitation events, among other strategies.
- Wildfire and landslide risk are often related and can result in destabilized slopes, destruction or blockage of roads and significant travel delays. Wildfires burn soil-stabilizing vegetation, and as a result create clearer and less stabilized paths for water and debris, making hilly areas more vulnerable to landslides. Landslide risk also increases with heavy precipitation if hillsides become saturated. Many adaptation strategies to mitigate wildfire and landslide risks involve different slope stabilization techniques such as using hard/grey infrastructure like retaining walls, adding horizontal drains in hillsides, flattening the angle of hillside slopes, or using biotechnical methods (vegetation) with root structures that reinforce soil and prevent or slow down runoff. Other strategies emphasize the importance of planning and locating routes out of high-risk areas as much as possible, providing route alternatives, and protecting evacuation routes.
The Adaptation Plan notes that these strategies all generally fall into one of four categories – maintain and manage; strengthen and protect; enhance redundancy; and retreat – which should be combined as needed to best address climate risks in the future. Although not addressed in the Adaptation Plan itself, the appendices also include reports that focus on risks related to drought; concerns and regulations related to environmental justice in implementing adaptation strategies; and governance issues.
For the first time, SACOG is incorporating climate adaptation into its 2016 Metropolitan Transportation Plan/Sustainable Communities Strategy (MTP/SCS) Update, “Building a Sustainable System” (the update to the region’s long-range transportation plan). The information about potential consequences of climate change for transportation assets and the examples and best practices included in the Adaptation Plan’s appendices are intended to provide a starting point for more in-depth risk assessment and development of adaptation strategies for specific assets. The Adaptation Plan also recommends four specific actions for implementing and integrating adaptation more fully into transportation investment planning in the future, including:
- Stakeholder engagement: “Form a Technical Advisory Committee to help guide ongoing climate adaptation planning, implementation and monitoring efforts.”
- Asset level assessments: “Work with stakeholders to conduct an asset level criticality and climate change vulnerability assessment on the region’s transportation network.”
- Climate adaptation in transportation funding: “Based on asset level criticality and climate change vulnerability assessments, work with the SACOG Board of Directors to determine how climate adaptation should be addressed in the biennial regional funding round.”
- Monitoring: “Work with stakeholders on long term monitoring of climate conditions and transportation infrastructure adaptability.”
These policies will help ensure that the overall transportation system successfully performs as envisioned in the MTP/SCS, despite increasing threats from climate change.
The final 2016 MTP/SCS update was adopted in February 2016 and it includes climate change adaptation as one of the new modifications to the plan. The information about climate risks and potential impacts to transportation infrastructure, as discussed in the Adaptation Plan, is incorporated in the MTP/SCS chapter on Environmental Sustainability (chapter 7). The MTP/SCS notes the need to build upon these adaptation efforts, suggesting that later work could include more in-depth asset-specific vulnerability assessments, analyses of the adaptive capacity of transportation systems, coordination with emergency management, and evaluation of specific adaptation strategies for future updates to the MTP/SCS.
SACOG developed its Adaptation Plan with help from CivicSpark, a program organized by the Local Government Commission in California that pairs AmeriCorps members with local jurisdictions to provide technical assistance for climate-change-related research, planning, and project implementation. The Adaptation Plan was developed between 2014 and 2015, and adopted unanimously by the SACOG Board of Directors in August 2015.
This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on March 31, 2016.
Publication Date: August 2015
- Sacramento Area Council of Governments (SACOG)
- Adaptation plan
- Plans (other)